Tracing stable isotopes (δ 2 H and δ 18 O) from meteoric water to groundwater in the Densu River basin of Ghana Dickson Adomako & Abass Gibrilla & Piotr Maloszewski & Samuel Yao Ganyaglo & Shive Prakash Rai Received: 15 July 2014 /Accepted: 1 April 2015 # Springer International Publishing Switzerland 2015 Abstract This study represents the first attempt to study soil water δ 18 O profiles in Ghana using a mechan- ical auger. In this paper, the characteristics of δ 18 O and δ 2 H in rain water, surface water, soil water and ground- water have been used to understand the transformation mechanism of rain water to groundwater. Rain waters were sampled in Koforidua and Accra. Surface water and groundwater were sampled from the Densu River and selected boreholes in the basin, respectively. Soil waters were taken from three typical sites, namely, Potroase (POT), Teacher Mante (TM) and Ayikai Doblo (AD) in the northern, middle and southern zone from 0.00- to 6-m depth. The soil water was extracted using vacuum distillation method. The distribution of the sta- ble isotopes of rain water is influenced by rainfall amount with minimal temperature effect. In general, the soil water is of meteoric origin undergoing fractionation-controlled evaporation. In the middle zone, the soil water shows some evidence of recharge from enriched source. The three profiles show similar trend of enriched values in the upper depths with grad- ual depletions of δ 18 O with depth. The POT profile showed relatively more depleted values suggesting a fast infiltration. In all the three profiles, soil waters below 3 m were found to contribute to groundwater recharge with piston flow as the dominant mechanism. The study also revealed that there is a significant con- tribution of enrich source to the groundwater system leading to the dilution of the infiltrating water by the large aquifer. Keywords Stable isotope . Soil water movement . Infiltration . Groundwater recharge . Groundwater . Densu River basin Introduction Groundwater plays an important role in the socio- economic development of many rural communities in Ghana. The study of groundwater systems requires data on hydrogeochemistry, piezometric and isotopic data. Groundwater studies in Ghana are mainly focused on water quality using hydrogeochemical and piezometric methods. However, due to large areal extent, complex hydrogeological conditions (multiple aquifers and flow systems) and scarce data, the use of these traditional methods for groundwater studies does not adequately provide deep understanding on groundwater recharge, circulation, flow mechanism, aquifer continuity, sources of ion in the water, etc. which are key issues for ground- water development and management. The use of Environ Monit Assess (2015) 187:264 DOI 10.1007/s10661-015-4498-2 D. Adomako : A. Gibrilla (*) : S. Y. Ganyaglo Nuclear Chemistry and Environmental Research Centre, National Nuclear Research Institute, Ghana Atomic Energy Commission, Box LG 80, Kwabenya-Accra, Ghana e-mail: gibrilla2abass@yahoo.co.uk P. Maloszewski Institute of Groundwater Ecology, Helmholtz Zentrum München-German Research Centre for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany S. P. Rai National Institute of Hydrology, Roorkee 247 667, India